Antarctica displaced Australia eastwards and this probably caused the eruption of
the Kerguelen flood basalts at a fault line. From the ridge line on the Google Earth
it suggests that the two continents travelled about 2600 km together (during a period
of about 26 million years - considering an average plate movement of 10cm/year).
Since about 34 mya, the opening of the Southern Ocean bed (developing on both sides
of the South-east Indian Ridge) moved Australia moved away from Antarctica and into
its present position. During that time the Kerguelen Igneous Province was separated
from another part of the same flood basalt at Broken Ridge.
I have depicted Antarctica’s entire movement and the estimated timeframe for this
sequence. Click on the image for larger version
So it can be seen why so many workers have assumed that Australia was originally
attached to Antarctica and have developed their models of Gondwana from this.
All small Earth protagonists have also been confused by these assumptions and this
has led to serious errors in their modelling.
The mid-ocean ridge between the two continents, the good fit together of the two
continents, along with the flood basalt areas - now in two sections - all conspire
to form this assumption.
However, my modelling shows that Antarctica had its origins as a land mass between
east Asia and South America, some 250 million years ago. Only within the last 65
million years has Antarctica been in the Indian Ocean area where it collided with
Australia in such a way as to change its shape (thus making it a near perfect fit).
Its final separation left the ridge marks between the two continents.
Summary on Post Clam-shell Expansion
While the Earth had being undergoing the lop-sided clam-shell expansion which affected
the Pacific and Indian Ocean areas mainly, the landmasses on the other side of the
planet were undergoing stretching in some areas as adjustments back to the Earth’s
rounded-ness needed to take place, on a regular basis. This process continued after
the clam-shell sequence had finished and involved the rupture of continental crust
on the western side and the development of new crustal material in the Atlantic and
Arctic ocean areas. These new ocean beds completed the fragmentation of Gondwana
and Laurasia into the continents we know today.